1. Technical Field
The present disclosure relates to an electrosurgical instrument and method for performing electrosurgical procedures. More particularly, the present disclosure relates to an open or endoscopic bipolar electrosurgical forceps that includes opposing jaw members each having a sealing plate for grasping tissue and supplying electrosurgical energy thereto. The pressure exerted by the sealing plates on the tissue is adjusted using a feedback control loop that utilizes gap distance between the sealing plates as a control variable.
2. Background of Related Art
Electrosurgery involves application of high radio frequency electrical current to a surgical site to cut, ablate, coagulate, cauterize, desiccate or seal tissue. Tissue or vessel sealing is a process of liquefying the collagen, elastin and ground substances in the tissue so that they reform into a fused mass with significantly-reduced demarcation between the opposing tissue structures. Cauterization involves the use of heat to destroy tissue and coagulation is a process of desiccating tissue wherein the tissue cells are ruptured and dried.
In bipolar electrosurgery, one of the electrodes of the hand-held instrument functions as the active electrode and the other as the return electrode. The return electrode is placed in close proximity to the active electrode such that an electrical circuit is formed between the two electrodes (e.g., electrosurgical forceps). In this manner, the applied electrical current is limited to the body tissue positioned between the electrodes. When the electrodes are sufficiently separated from one another, the electrical circuit is open and thus inadvertent contact with body tissue with either of the separated electrodes does not cause current to flow.
A forceps is a pliers-like instrument that relies on mechanical action between its jaws to grasp, clamp and constrict vessels or tissue. So-called “open forceps” are commonly used in open surgical procedures whereas “endoscopic forceps” or “laparoscopic forceps” are, as the name implies, are used for less invasive endoscopic surgical procedures. Electrosurgical forceps (open or endoscopic) utilize mechanical clamping action and electrical energy to effect hemostasis on the clamped tissue. The forceps includes electrosurgical sealing plates that apply the electrosurgical energy to the clamped tissue. By controlling the intensity, frequency and duration of the electrosurgical energy applied through the sealing plates to the tissue, the surgeon can coagulate, cauterize and/or seal tissue.
Tissue sealing procedures involve more than simply cauterizing tissue. In order to affect a proper seal in vessels or tissue, it has been determined that a variety of mechanical and electrical parameters must be accurately controlled: the pressure applied to the tissue; the gap distance between the electrodes (i.e., distance between opposing jaw members when closed about tissue); and amount of energy applied to tissue.
Numerous electrosurgical instruments have been proposed in the past for various open and endoscopic surgical procedures. However, most of these instruments cauterize or coagulate tissue and are not designed to create an effective or a uniform seal. Other instruments generally rely on clamping pressure alone to procure proper sealing thickness and are often not designed to take into account gap tolerances and/or parallelism and flatness requirements, which are parameters that, if properly controlled, can assure a consistent and effective tissue seal.